Fix dependency: liblas -> libblas
Remove libblass dependency
prevent NaN generation when gravity is (0, 0, 0) and we switch from body is excluded to body is not excluded in gravity force appliction.  This is necessary as the rest of the code skips updates when gravity is special cased to zero.

(cherry picked from commit dd1b1a9eabbf87fc7a973b53b16da8381a2f1f5e)